2: Improve the effectiveness, energy efficiency, and economics of water reuse and waste treatment technologies and practices. This will include developing technologies to minimize waste and reclaim water, protein, and/or energy to improve the economic and environmental sustainability of closed-containment systems.

• 2.1 Economic evaluation and life cycle assessment of land-based closed-containment systems for production of food-size Atlantic salmon and rainbow trout.
• 2.2 Development of low-head and high-volume gas transfer processes to improve the energy efficiency of RAS.
• 2.3 Improve technologies and practices that counter the effects of fish pathogens, and reduce the need for chemotherapeutic and antibiotic use within closed-containment production systems.
• 2.4 Optimize cell age within MBR systems to maximize metals removal and protein content of waste mixed liquor suspended solids.

3: Conduct production trials of fish and feeds developed through ARS collaborations.

1b.Approach (from AD-416):
Research at The Conservation Fund’s Freshwater Institute focuses on developing and improving technologies to enhance the sustainability and reduce the environmental impact of the modern fish farming industry. To this end, the proposed projects listed in this plan will continue our work in pioneering land-based, closed containment water recirculation systems that are biosecure, have an easily controlled rearing environment, produce healthy and optimally performing fish, and produce manageable effluent for significant reduction in waste discharge. Specifically, our proposed research will investigate, among other things, the biological and economic feasibility of raising Atlantic salmon to market size in freshwater recirculation systems (as opposed to coastal net-pens); the potential for raising rainbow trout in semi-closed or closed water recirculation systems to further reduce the amount of influent water and point source discharge required for these systems; the health and welfare of salmon and trout in relation to dissolved oxygen and carbon dioxide levels, swimming speed in circular tanks, soy-based feeds, and water ozonation in low-exchange systems; and the potential for greater energy efficiency in water recirculation systems through improved low-lift pumping and gas transfer processes. In addition, our experimental systems will continue to serve as field testing sites for alternative-protein feeds and for salmon and trout strains selected through genetic improvement programs at other USDA facilities. The investigations proposed in this plan will build on the findings of previous years of USDA-funded research to develop a sustainable, environmentally responsible, and economically viable aquaculture industry in the United States.

1. Identify criteria to optimize the performance, health, welfare and consumer value of Atlantic salmon and other salmonids grown to food-size in intensive, land-based, closed-containment systems.

2. Improve the effectiveness, energy efficiency, and economics of water reuse and waste treatment technologies and practices. This will include developing technologies to minimize waste and reclaim water, protein, and/or energy to improve the economic and environmental sustainability of closed-containment systems.

3. Conduct production trials of fish and feeds developed through ARS collaborations.

3.Progress Report:
The overall goal of this project is to develop and improve technologies that enhance the sustainability and reduce the environmental impacts of the modern fish farming industry. Progress was made in several areas.

Research on Atlantic salmon performance, health, and welfare, plus system water quality, was completed in replicated water recirculating systems that were operated at either high makeup water (2.5% flow exchange) or low makeup water (0.25% flow exchange) flushing rates. This work has provided valuable information to producers intent on rearing Atlantic salmon in closed-containment systems up to market size in fresh water.

The economics and sustainability of large-scale land-based closed-containment systems for Atlantic salmon growout were investigated. A preliminary life cycle assessment was completed to quantify greenhouse gas and energy use impacts of the model facility and the highlights from the economic model were published in a report. We also collaborated with researchers at SINTEF (Norway) to determine differences in fixed and variable costs and environmental impacts of land-based and net pen salmon production systems based on a standardized evaluation.

Experiments were completed to identify the cost effectiveness of anoxic fluidized-sand biological reactors using heterotrophic denitrification to convert nitrate in the water to benign dinitrogen gas. Organic carbon that is necessary to drive denitrification was supplied by organic acids that were recovered from the supernatant exiting the gravity thickening tanks used to dewater biosolid waste. Findings will provide lower cost yet effective technology to remove nitrate nitrogen from effluent waters of land-based closed-containment systems.

Selected Atlantic salmon (NCWMAC, Franklin, ME) germplasm resources, one group diploid and the other triploid, were cultured from parr to post-smolt size in a growout trial within a commercial-scale intensive water recirculating systems.

4.Accomplishments
1.
Chronic nitrate exposure impacts health and welfare of farmed rainbow trout. The fish industry has significant concerns about the impact of nitrate nitrogen on fish health and production. Through ARS-funded research at The Freshwater Institute's Conservation Fund in Shepherdstown, West Virginia, juvenile rainbow trout were cultured in replicated water recirculation aquaculture systems, half that were maintained at elevated nitrate nitrogen concentrations and the other half at more moderate concentrations. Over the three-month study period, rainbow trout growth was not negatively impacted by the high nitrate treatment; however, cumulative survival for fish cultured within the high nitrate aquaculture systems was lower and resulted in total fish biomass being significantly lower than in the low nitrate group. Rainbow trout swimming behavior was also significantly different between treatments, with higher average swimming speeds and increased side-swimming in the high nitrate treatments. The results of this study provided strong evidence that higher nitrate levels (e.g. 80-100 mg/L) are related to chronic health and welfare impacts on juvenile rainbow trout under the described conditions, and have broader implications pertaining to fish health in wild populations existing in watersheds contaminated with high levels of nitrate nitrogen. For the US rainbow trout industry, these results provide valuable water quality guidance to limit the impacts of nitrate nitrogen on farmed fish populations.